This invention relates to controlling output of power systems. Particularly, the invention relates to the conduction of power to the electrical devices.
In many situations it is desireable to control the application of power to power-using devices. Particularly, it is important to control the output of such devices by controlling the power supply to the devices. For example, the outputs of motors are controlled by the application of power to the motors. The illumination of lamps is controlled by the control of power to the lamps.
In incandescent lamps, power may be readily adjusted by varying resistance or by adjusting potentiometers or by controlling alternate voltage forms with the effect of reducing voltage to lamps and reducing power to lamps.
In some illumination forms, it is difficult to reduce illumination by reducing voltage or power since the forms depend on precise voltages and powers for continued illumination. Reducing or interrupting voltages to such lamps may cause extinguishing or flickering or may reduce lamp life or may reduce the life of operating systems associated with such lamps.
A widely used source of illumination is fluorescent lamps. It has been reported that fluorescent lamps provide the majority of all artificial illumination. Some reports indicate up to 80 percent or more of illumination in developed countries is provided by fluorescent lamps. It is difficult at best and very expensive when possible to change the illumination from fluorescent lamps by changing power. Ordinary wall dimmers for incandescent lamps are ineffective.
While it may be possible to wire separate banks of lamps controlled by separate switches to change illumination within rooms, such separate wiring adds difficulty and expense and materials and labor. Retrofitting old constructions with multiple separately-controlled circuits is expensive and in some cases is extremely difficult.
The present invention overcomes difficulties of the prior art.